Abstract

Delocalized transport in a batch of amorphous carbon thin films is shown via a positive slope of the reduced activation energy below a certain temperature and a large value of conductivity minima. A crossover of dimensionality from three-dimensional (3D) to two-dimensional (2D) weak localization below the transition temperature and a signature of electron-electron interactions in 3D can be found in these films, which is significantly different from many other forms of carbon. The dimensionality crossover suggests 2D resonant tunneling between carbon clusters due to the increase of the phase coherence length and a low tunnel effective mass of electrons.